Many of Massachusetts's health reforms have brought about positive change: the number of uninsured has fallen by half, access to needed care has increased, and private insurance has not been "crowded out" by public insurance programs. But the Massachusetts initiative has also seen higher than anticipated costs. In a new analysis, John Holahan and Linda Blumberg summarize the state's accomplishments, examine the challenges, and suggest four options for addressing long-term costs. According to the authors, much of Massachusetts's high spending growth is due to the concentration in the state's hospital and insurance markets.